I have, Origin (which was compromised many times in July 2017 even with 2FA on the account and my email, never buying an EA game again), uPlay (again compromised with 2FA on...), Steam, GOG, Greenmangaming (promo form years ago that gave away a free game), chrono.gg, amazon, Nintendo store for my DSes, and I am probability forgetting some.

Granted only Origin, uPlay, Steam, and GoG (optional) are clients/starters but still.